Although general purpose computers have been available for more than 40 years, the dramatic plunge in the cost of electronics in the past 10 years has finally made significant computing power affordable to almost anyone. However, a large number of people including professionals have little idea of how a computer really works or what it can and cannot do. Presented here is an introduction to the hardware and software of microcomputers which assumes no working knowledge of electronics or programming. The fundamental pieces of a microcomputer are explained, giving some insight into the reasons why present microcomputers are built the way they are. This is followed by a discussion of the fundamentals of how software is used to make the hardware compute. The various levels of software are discussed, then the most commonly used types of user application software are described, and finally some suggestions are made on how to choose a personal computer.